WordPress at a glance
action is not described

check_passwords action-hook . WP 1.5.1

Fires before the password and confirm password fields are checked for congruity.

Usage

add_action( 'check_passwords', 'action_function_name_2690', 10, 3 );
function action_function_name_2690( $user_login, $pass1, $pass2 ){
	// action...
}
$user_login(string)
The username.
$pass1(string)
The password (passed by reference).
$pass2(string)
The confirmed password (passed by reference).

Where the hook is called

edit_user()
check_passwords
wp-admin/includes/user.php 140
do_action_ref_array( 'check_passwords', array( $user->user_login, &$pass1, &$pass2 ) );

Where the hook is used (in WP core)

Does not used.